The Kingdom Protista

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The Kingdom Protista

• Heterotrophic Protists
• Part I Sarcodines Ciliates

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Protozoans

• The kingdom protista contains a diverse
  collection of organisms ---animal-like,
  plant-like and fungus-like organisms. All of
  them are eukaryotic, and lack any tissue
  differentiation.

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General Characteristics Protozoa are
single-celled microscopic. Many have a means
of locomotion or motility.

• 1) They live in a variety of environments
  freshwater rivers and ponds, some drift in the
  ocean, some live in soil, some live in the
  bodies of other organisms.
• 2) Some are free-living, while some are
  parasitic.
• 3) They are heterotrophic, obtaining
  nutrients by ingesting small molecules or cells.
• 4) Many species make up zooplankton, which
  are a primary
• food source of aquatic ecosystems.

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• 5) They can reproduce by binary fission, (some by
  multiple fission), while can reproduce sexually
  by conjugation.

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B) SARCODINES

• 1) Habitat bottom of slow-moving fresh-water
  streams and ponds, on leaves of water plants,
  moist soil, mud, on rocks, and saltwater.

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2) Movement through pseudopodia- caused by
cytoplasmic streaming

• Cytoplasmic Streaming (ameboid movement) most
  sarcodines
• have flexible cell membranes and form cytoplasmic
  extensions called
• pseudopodia (singular pseudopod)
• Inner cytoplasm called endoplasm pushes an outer
  layer called ectoplasm to form blunt, arm-like
  extensions.
• Other pseudopodia retract as cytoplasm flows in
  the direction of the
• new cytoplasm.

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• 3) Feeding Sarcodines feed on other protists
  which they engulf by phagocytosis.

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• Food is surrounded or engulfed
  by pseudopodia.
• A portion of the membrane surrounds the food,
  pinches off forms a food vacuole which enters
  the cell. This process is known as endocytosis.
• phagocytosis
  pinocytosis

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• Food is digested in the vacuole. Nutrients are
  distributed throughout the cytoplasm. Wastes exit
  the cell through the reverse process called
  exocytosis.

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• 4) Excess water removal Due to the hypotonic
  conditions of the surrounding environment, the
  freshwater sarcodines must constantly rid
  themselves of excess water that diffuses into the
  cell. Most freshwater sarcodines expel water with
  an organelle called a contractile vacuole.

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• 5) Reproduction
• Binary Fission

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6) Human Diseases

• Amebic dysentery caused by Entamoeba
  histolytica- serious illness caused by ingesting
  contaminated food or water. They form cysts that
  survive unfavorable conditions for months. It
  infects the large intestine and produces ulcers
  via digestive enzymes.
• Diarrhea, and intense pain, as well
• as damage to other organs as the
• amoebas may travel thought the
• blood to other organs.
• Usually common to Mexico, part of South America,
  West Coast of Africa, and parts of South East
  Asia.

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7) Interesting sarcodines

• Foraminifera ancient group of shell covered
  sarcodine found primarily in oceans. The calcium
  carbonate shell is called the test.
• Deposits of these organisms shells have formed
  calcium rich sedimentary layers of chalk
  deposits.

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• Millions of years of deposits have formed the
  white cliffs of Dover in England, and were a
  source of limestone for the Great Pyramids of
  Egypt.

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• Radiolarians the oldest group which have a
  silicon dioxide test with a radial arrangement of
  spines that extend from the shell.
• With their glassy skeleton of almost perfect
  geometric form and symmetry, they are among the
  most beautiful of all protists. ---

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Difflugia

• At only about one tenth of a millimeter long,
  is a testate rhizopod (difflugia) - a species of
  amoeba that lives inside a balloon-shaped shell.
  Testate rhizopods either secrete their shells or
  they cement minute sand grains together to create
  one. When you think about it, that's a remarkable
  feat of construction for one of the lowest forms
  of life that, superficially, is little more than
  a slithering blob of cytoplasm.
• normal light polarized
  light microscopy

Under polarized light the quartz grains of the
shell diffuse the light into many colors.
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The Brain Eating Amoeba

• (9/29/07) 6 die from brain-eating amoeba in warm
  lake waters (Arizona)
• Doctors said Aaron Evans, a 17 year-old who died
  after swimming, probably picked up the amoeba in
  the balmy shallows of Lake Havasu, a popular
  man-made lake on the Colorado River between
  Arizona and California.

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• It sounds like science fiction but it's true A
  killer amoeba living in lakes enters the body
  through the nose and attacks the brain where it
  feeds until you die.

Immunoflurescent reaction of the organism as
flagellated cells, cysts and
tropozoite forms.
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• People become infected when they wade through
  shallow water and stir up the bottom. If someone
  allows water to shoot up the nose - say, by doing
  a somersault in chest-deep water - the amoeba can
  latch onto the olfactory nerve. The amoeba
  destroys tissue as it makes its way up into the
  brain, where it continues the damage, "basically
  feeding on the brain cells," Beach said.

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• People who are infected tend to complain of a
  stiff neck, headaches and fevers. In the later
  stages, they'll show signs of brain damage such
  as hallucinations and behavioral changes, he
  said.
• Infection with Naegleria causes the disease
  primary amebic meningoencephalitis (PAM), a
  brain inflammation, which leads to the
  destruction of brain tissue.

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• Initial signs and symptoms of PAM start 1 to 14
  daysafter infection. These symptoms include
  headache,fever, nausea, vomiting, and stiff neck.
  As the amoebae cause more extensive destruction
  of brain tissue this leads to confusion, lack of
  attention to people and surroundings, loss of
  balance, seizures, and hallucinations. After
  onset of symptoms, the disease progresses rapidly
  and usually results in death within 3 to 7 days.
  (from CDC Fact Sheet)

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• 2) Movement short hair-like projections similar
  to flagella. The cilia beat in
• synchronized strokes that pass in waves
• across the cell causing the protozoan to
  rotate on its axis.

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3) Feeding

• Cilia is used to obtain food beating cilia
• create water currents that sweep food in the
• organism.

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Paramecium Feeding

• 1) A funnel-shaped depression in the
• pellicle layer called the oral groove, is
• lined with cilia the bring in food.
• (pellicle layer - a clear elastic layer of
• protein that surrounds the cell membrane
• to help maintain shape)
• 2) Food moves down the groove to
• the mouth pore, into the gullet.
• 3) Food vacuoles form at the gullet which
• circulate through the cytoplasm. Organic
• molecules are digested and absorbed.
• 4) Waste moves to the
• anal pore and is
• expelled.

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• Excess water removal Paramecia use contractile
• vacuoles near the surface on the side opposite
  the oral
• groove, one at the front end (anterior) and one
  at the
• rear (posterior).
• It is more complicated that the amoebas due the
• presence of a circle of canals that radiate from
• the vacuole, some distance into the cytoplasm.
• The canals fill with fluid, which discharge into
  the
• central vacuole. The vacuole then ejects the
  fluid from
• the cell.

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• The canals fill with fluid, which discharge
  into the central vacuole. The vacuole then ejects
  the fluid from the cell.

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• 5) Defense Mechanism Beneath the outer
  covering, and embedded in the clear outer
  cytoplasm, are small oval bodies called
  trichocysts. These bodies can be discharged to
  the exterior. During the process they become
  greatly elongated into fine threads.

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• It is thought that they are discharged when
  the paramecium is attacked. Scientists have
  reported that they may act as harpoons.
• They are shot out in less than a millisecond.
• The rapid firing of trichocysts also rapidly
  propel the paramecium away from danger.
• They also may be used by the paramecium to
  anchor itself while feeding on bacteria.

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• Reproduction Paramecium may reproduce
• sexually through conjugation. Paramecia from
• opposite mating strains line up and join
• together. It involves macro micronuclei.
• Following conjugation, each paramecium
• divides by binary fission.

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Paramecia conjugating